Lithium Abundance - World Lithium Reserve

Saturday, March 29, 2008

In 1976 a National Research Council Panel estimated that Western World lithium reserves and resources totaled 10.6 million tonnes as elemental lithium.

Subsequent discoveries, particularly in brines in the southern Andes and the plateaus of western China and Tibet have increased the tonnages significantly. Geothermal brines and lithium bearing clays add to the total.

This current estimate totals 28.4 million tonnes Li equivalent to more than 150.0 million tonnes of lithium carbonate of which nearly 14.0 million tonnes lithium (about 74.0 million tonnes of carbonate) are at active or proposed operations.

This can be compared with current demand for lithium chemicals which approximates to 84,000 tonnes as lithium carbonate equivalents (16,000 tonnes Li).

Concerns regarding lithium availability for hybrid or electric vehicle batteries or other foreseeable applications are unfounded.

In 1975 the United States Geological Survey convened a symposium in Golden, Colorado, on lithium demand and resources prompted by the premise that lithium resources would be inadequate to meet future demand in fusion power generation (expected from the Year 2000 onward!) and in load leveling storage batteries. Demand estimates were astronomic and in the light of these projections the availability of adequate reserves was seriously questioned. In the introduction to the symposium reference was made to the “gravity” of the impending shortage of lithium. (Anon 1976)

Fortunately, shortly afterwards, at the request of the United States Energy Research and Development Administration, the National Academy of Sciences and Engineering formed a National Research Council Committee on Nuclear and Alternative Energy Systems (CONEAS) to report on the role of nuclear power in the context of alternative energy systems in the time period 1985 to 2010. CONEAS was organized into four main panels and twenty-six sub panels and the Lithium Sub Panel was one of these asked to report on raw material availability.

This group was chaired by Dr. Thomas Kesler, formerly with the USGS and the leading authority on the North Carolina tin-spodumene belt the, then, dominant source of lithium, Dr. James Vine of the USGS and the head of its Lithium Resource Appraisal Group, Dr. Ihor Kunasz of the Foote Mineral Company and the writer representing Lithium Corporation of America. The panel reported in 1976 (Evans, 1978) and some of the figures used in this current paper are based on that report.

The tonnage estimated in the panel report of 10.65 million tonnes of Li was in respect of the Western World as little data were available in respect of Russia and China.

In 1985, fresh concerns about lithium availability arose from a different group of researchers and aluminium producers when it seemed a possibility that lithium-aluminium alloys for aircraft would create a major demand and the writer produced an updated report based on new discoveries in the preceding ten years (Evans 1986).

Additions to the 1978 paper included the estimated reserves in the Greenbushes spodumene pegmatite in Western Australia, the brines of the Salar de Uyuni in Bolivia, the lithium in geothermal brines in Southern California and the lithium contained in hectorite deposits in the Western USA.

Recently, concern has again been expressed about lithium availability (Tahil, 2007) because of the potential very large scale use of lithium carbonate, in particular, in lithium-ion batteries in hybrid and all-electric motor vehicles and this has precipitated the preparation of this report.

Actual and potential sources of lithium are from pegmatites, continental brines, geothermal brines, oilfield brines and the clay mineral hectorite.

PEGMATITES - are course grained igneous rocks formed by the crystallization of post magmatic fluids. They occur in close proximity to large magmatic intrusions. Lithium containing pegmatites are relatively rare and are most frequently associated with tin and tantalite. Many of the lithium ‘discoveries’ resulted from the exploration for these associated minerals.

The principal lithium pegmatite minerals are spodumene, petalite (both lithium-aluminium silicates) and lepidolite (a lithium mica) which normally contains minor quantities of cesium, rubidium and fluorine. All have been used directly in the glass and ceramic industries provided the iron content is low and all have been used as the feedstock for the production of lithium chemicals. Spodumene, as a concentrate, is still used in China for lithium chemical production and new production is planned in Europe and Australia.

CONTINENTAL BRINES - these brines with the lithium derived mainly from the leaching of volcanic rocks vary greatly in lithium content largely as a result of the extent to which they have been subject to solar evaporation. They range from between 30 to 60 ppm in the Great Salt Lake, Utah, where the evaporation rates are modest and dilution is constant due to the high volume of fresh water inflow, through the subsurface brines in Searles Lake California (a former location of lithium production) and Silver Peak, Nevada (a current source) to the high altitude salars in Bolivia, Argentina, Chile, Tibet and China where lithium concentrations can be very high.

GEOTHERMAL BRINES - the author is not aware of any publications that provide a listing of the lithium content of all known geothermal brines. Small quantities are contained in brines at Wairakei, New Zealand (13ppm Li) at the Reykanes Field (8ppm) and other areas in Iceland and at El Tatio in Chile (47ppm). The most attractive known occurrences are in the the Brawley area south of the Salton Sea in Southern California.

OILFIELD BRINES - large tonnages of lithium are contained in oil field brines in North Dakota, Wyoming, Oklahoma, east Texas and Arkansas where brines grading up to 700mg/lt are known to exist. Other lithium brines exist in the Paradox Basin, Utah and but the author is unaware of any global review of the potential.

HECTORITE CLAYS - hectorite is a magnesium lithium smectite and the clay is found in a number of areas in the western United States. The largest known deposit is associated with the volcanic rocks of the McDermitt caldera that straddles the Nevada/Oregon border where it occurs in a series of elongate lenses. Current drilling is confirming earlier work that indicated very large tonnages of contained lithium.

At the time of the National Research Council report the production of lithium chemicals was a duopoly in the Western world and demand at that time approximated to 3,200 tonnes/year of Li. Little was known about Russian and Chinese production and reserves.

The two main producers were Lithium Corporation of America (LCA) and the Foote Mineral Company. Both processed spodumene concentrates from their mines near Bessemer City and Kings Mountain, North Carolina.

In 1975 Foote, then owned by Cyprus Minerals, signed an agreement with CORFO, a Chilean Government agency and owner of the mineral claims covering the nucleus of the Salar de Atacama to evaluate the brine deposit there. At the end of the evaluation the company was allowed to lease a percentage of the claims. Sociedad Chileno de Litio was formed and production commenced in 1984. Foote/Cyprus was subsequently purchased by Chemetall and later by Rockwood Holdings.

In 1980, Amax Exploration visited the Salar as part of a global search for potash but on discovering that the Foote agreement granted them exclusive rights for lithium recovery for only eight years pressed for the right to co-produce lithium. In 1984 CORFO invited bids for the development of much of the remainder of the Salar’s nucleus. Amax were successful in bidding against LCA (which, by then had been purchased by FMC Corp.) but Amax, following the completion of an evaluation programme, decided to dispose of its interest and this was acquired by Socieded Quimica y Minera (SQM) a major producer of iodine and sodium nitrate. SQM came into production at the Salar in 1997. The production duopoly was now broken and to acquire market share and with its low costs SQM substantially reduced the price of lithium carbonate.

Having lost the bid in Chile, FMC turned its attention to the Salar de Uyuni in Bolivia but failed in its negotiations with the Government there but successfully negotiated with the Argentinian authorities for rights to the Salar de Hombre Muerto. Although a much smaller salar the brine is an extremely ‘clean’ one and produced a quality of lithium chloride unavailable elsewhere. However, both capital and operating costs were much greater than anticipated and carbonate production was suspended for several years. FMC became reliant upon SQM for carbonate.

The North Carolina pegmatite mines closed with the development of the lower cost reserves in Chile and Argentina.

Another producer Admiralty Resources, plans to come on stream in 2008 from shallow brines at the Salar de Rincon in Argentina.

In the early 2000’s after the evaluation of the very large brine deposits in the Qaidam Basin in Northwest China, a technical breakthrough was achieved in the processing of brines with a high magnesium content. Subsequently, major discoveries were made on the Tibet Plateau. Prior to the brine developments China produced lithium chemicals from domestic pegmatite sources and imported spodumene concentrates.

Since the National Research Council report other low iron sources of lithium ore for direct usage have been developed so now there are three – Bikita in Zimbabwe, Bernic Lake in Canada and Greenbushes in Australia. The last of these attempted to enter the chemical business but failed. Direct usage ores have some significance in chemical demand in that they compete with carbonate in certain applications.

In the case of production from pegmatites, assuming the most common acid leach process is used, they comprise mining, beneficiation to a moderate or high grade of concentrate, calcination to produce acid-leachable beta spodumene, reaction with sulphuric acid and the conversion of the lithium sulphate solution with sodium carbonate. The costs of acid, soda ash and energy are a very significant percentage of total costs but they can be partly offset if a market exists for the sodium sulfate by-product.

In the case of hectorite clays, geothermal brines and oilfield brines lithium recovery costs have not been developed but work is current on the first two of these potential sources.

In the case of continental brines which are the current major source costs, probably, vary greatly. As with the case of pegmatites the cost of soda ash to convert lithium chloride to lithium carbonate is very significant. Brine grades vary greatly ranging currently in the Andes, from approximately 0.3% Li at the SQM operation in Chile to 0.062% and 0.034% at the two Argentinian salares of Hombre Muerto and Rincon respectively.

The most deleterious element in the brine is magnesium and the magnesium/lithium ratio is relatively low at the Salar de Atacama, very low at the Salar de Hombre Muerto and high at the Salar de Rincon. The largest of the Chinese brine deposits also has a very high ratio and these brines need more complex processing.

The other important factor in the brine chemistry is the presence or not of other recoverable products.

In Chile, Rockwood Holdings, now the owner of Chemetall who purchased Foote/Cyprus recover moderate tonnages of potassium chloride as a co-product at their operation and SQM recover much larger tonnages together with potassium sulphate and boric acid. Most of SQM’s potassium chloride is converted to much higher value potassium nitrate using nitrates from company owned deposits located between the salares and the Pacific coast.

At the Salar de Rincon potash recovery is planned and most of the Chinese salars contain economic concentrations of potassium and boron.

Another factor affecting capital costs apart from brine grade is the net evaporation rate which determines the area of the evaporation ponds necessary to increase the grade of the plant feed. These are a major capital cost but not a factor at the FMC operation where the lithium chloride is recovered directly from the in situ brine.

In the case of the one geothermal source discussed later the brine is rich in zinc a co-product as well as lithium and is a major producer of electric power but, as is with the case of oil field brines and hectorites, lithium recovery costs have not been determined.

The two North Carolina operations closed with the development of lower cost sources in Chile but could, should a massive demand materialize and prices rise as a result, be reactivated.

Based on figures used in the Lithium Panel report and later reserve data it is estimated, very approximately, that the FMC and former Foote operations contained reserves of 80,000 and 150,000 tonnes Li respectively at the time both operations were closed.

The Panel, based principally on Kesler’s very extensive work along the 48km long belt estimated a potential recoverable resource down to a depth of 1,500 metres of 375 million tonnes of ore at a grade typical of the area thus containing 2.6 million tonnes Li.

Other known pegmatite sources are small.

Continental Brines:

The Panel report listed tonnages for three brines – at Searles Lake, California, at Silver Peak, Nevada and the Great Salt Lake, Utah.

At Searles Lake lithium was recovered as a by-product from the commercial production of soda ash, potash and borax. The lithium was essentially a contaminant and with a process modification production ceased in 1978. It is highly improbable that lithium recovery will take place in the future. Silver Peak commenced production in the 1960’s pumping brines varying from 100 to 300 ppm Li. It continues to operate and the remaining economic reserves are estimated at 40,000 tonnes Li.

In the Great Salt Lake the overall tonnage of contained lithium approximates to 520,000 tonnes but the grade is very much lower than other brines considered as potential reserves in this report.

Geothermal Brines:

At the Salton Sea KGRA in southern California a brine with very high concentrations of potash, lithium, boron, zinc and lead is used to produce 288 megawatts of electric power.

A 30,000 tpa high grade zinc plant based on the brine has experienced technical problems but the brine also grades about 200 ppm Li and the throughput contains approximately 16,000 tpa Li. (William Bourcier, Lawrence Livermore National Laboratory, personal communication). Earlier (Duyvestein, 1992) calculated a similar figure of approximately 11,900 short tons of carbonate per 50 MW of capacity.

To put a reserve tonnage to the annual rate a 20 year life is assumed to give a figure of 316,000 tonnes Li.

There are other sites in the area with high lithium values.

Further north at the Mammoth Lakes geothermal field with a much lower lithium concentration, Lawrence Livermore Labs have a current project aimed at silica recovery which would be a first step in recovering lithium from brines of this nature

Oilfield Brines:

Collins (1978) estimated a possible reserve of 0.75 million tonnes of Li in one tenth of the area underlain by the Smackover Formation which extends through North Dakota, Wyoming, Oklahoma, east Texas and Arkansas. Other lithium-containing brines exist in the Paradox Basin, Utah.

Hectorites:

At the McDermitt Caldera on the Oregon/Nevada border, Western Uranium Corporation are re-examining seven lenses of hectorite clay originally drilled by Chevron Resources.

Drilling at the most southerly site, the PCD lens, is confirming the tonnage and grade indicated by Chevron. This lens has a length of about 2 kms, a width of approximately one kilometer and a thickness of 100 metres under shallow overburden. Higher grade portions of the deposit grade over 0.35% Li and the cut off used in the reserve calculation is 0.275% Li.

Chevron reported that the total resource contained 23.9 billion lbs of carbonate – 2 million tonnes of Li and test work on recovery methods is currently being undertaken.

Hectorites are known to occur elsewhere in the western United States but no reserve data exist.